Method for producing an inner ring for a tapered roller bearing, and tapered roller bearing having an inner ring

Abstract

Tapered roller bearings and methods of producing the same are disclosed. One method is for producing an inner ring for a tapered roller bearing in which the inner ring comprises a raceway portion and a fixed edge portion. The method may include providing an inner ring blank and an unfinished fixed edge portion. The inner ring blank may include an unfinished raceway portion and the unfinished fixed edge portion may have a larger outside diameter than the unfinished raceway portion. The inner ring blank may have a through-opening. The inner ring blank may be formed into the inner ring by extrusion in a main forming step, the unfinished fixed edge portion being transformed into the fixed edge portion and the unfinished raceway portion being transformed into the raceway portion. The inner ring may be formed in its final contour without any cutting.

Claims

1. A method for producing an inner ring for a tapered roller bearing in which the inner ring comprises a raceway portion and a fixed edge portion, comprising the following steps: providing a flat circular blank parted from a metal strip; removing a center part from the flat circular blank to form an annulus; forming the annulus into an inner ring blank by extrusion in a preliminary forming step, in which the inner ring blank comprises a continuous conical surface that includes a conical unfinished raceway portion and a conical unfinished fixed edge portion, in which the conical unfinished fixed edge portion has a larger outside diameter than the conical unfinished raceway portion, and in which the inner ring blank has a through-opening; and forming the inner ring blank into the inner ring by extrusion in a main forming step, the conical unfinished fixed edge portion being formed into the fixed edge portion and the conical unfinished raceway portion being formed into the raceway portion; wherein a final contour of the inner ring is formed without any cutting.

2. The method as claimed in claim 1, wherein the fixed edge portion comprises a check surface for tapered rollers of the tapered roller bearing, the check surface being formed toroidally in the main forming step.

3. The method as claimed in claim 1, wherein the inner ring blank comprises an unfinished flanged edge portion and the inner ring comprises a flanged edge portion, the unfinished flanged edge portion being transformed into the flanged edge portion in the main forming step.

4. A method for producing an inner ring for a tapered roller bearing, comprising: providing a flat circular blank; removing a center part from the flat circular blank to form an annulus; extruding the annulus into an inner ring blank in a preliminary forming step, the inner ring blank including a continuous conical surface that includes a conical unfinished raceway portion and a conical unfinished fixed edge portion, the conical unfinished fixed edge portion having a larger outside diameter than the conical unfinished raceway portion, and the inner ring blank having a through-opening; and extruding the inner ring blank into the inner ring in a main forming step, the conical unfinished fixed edge portion being formed into a fixed edge portion and the conical unfinished raceway portion being formed into a raceway portion; wherein a final contour of the inner ring is extruded without any cutting.

5. The method as claimed in claim 4, wherein the fixed edge portion comprises a fixed edge having a check surface for tapered rollers of the tapered roller bearing, the check surface being formed toroidally in the main forming step.

6. The method as claimed in claim 4, wherein the inner ring blank comprises an unfinished flanged edge portion and the inner ring comprises a flanged edge portion, the unfinished flanged edge portion being transformed into the flanged edge portion in the main forming step.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features, advantages and effects of the disclosure emerge from the following description of embodiments of the disclosure, and from the figures attached, of which:

(2) FIG. 1 shows a schematic longitudinal section along a main axis of rotation of a tapered roller bearing as an exemplary embodiment of the disclosure;

(3) FIG. 2 shows a schematic illustration of the method for producing an inner ring and optionally, in addition, an outer ring for the tapered roller bearing in FIG. 1; and

(4) FIGS. 3a, 3b, 3c show various optional details of the inner ring and a toroidal tapered roller.

DETAILED DESCRIPTION

(5) FIG. 1 shows a schematic longitudinal half-section of a tapered roller bearing 1 along a main axis of rotation H as an exemplary embodiment of the disclosure. The tapered roller bearing 1 comprises an inner ring 2, an outer ring 3 and multiple tapered rollers 4, which are arranged so that they roll between the inner ring 2 and the outer ring 3. The tapered roller bearing 1 is embodied as a single-row tapered roller bearing. The tapered roller bearing 1 is embodied, in particular, as a radial rolling bearing in which the contact angle 5 is between 0 and 45 degrees.

(6) The tapered rollers 4 have a truncated-cone shape with a conically tapering bearing surface 6. The tapered rollers 4 furthermore each have a small end face 7 and a large end face 8. An axis of rotation 9 of the tapered rollers 4 is arranged inclined in relation to the main axis of rotation H.

(7) The outer ring 3 has a cylindrical outer surface 10 and a conical inner raceway 11 oriented radially inwards for the tapered rollers 4. The outer ring 3 is produced in one piece. In particular, the outer ring 3 may be made of metal, such as steel. Here the outer ring 3 at its thickest point has a wall thickness c2.

(8) The inner ring 2 has a cylindrical inner surface 12, which defines a through-opening of the inner ring 2. The outer cylindrical surface 10 serves for mounting in a first support structure, such as a socket or a bore, for example; the inner cylindrical surface 12 serves for mounting on a second support structure, such as a spindle or a shaft, for example.

(9) The inner ring 2 may be divided in an axial direction to the main axis of rotation H into a raceway portion 13 and a fixed edge portion 14. The raceway portion 13 forms a raceway 15, in particular a contact surface or bearing surface, on which the tapered rollers 4 roll. The raceway 15 is embodied as an outer raceway of the inner ring 2 and has a conical shape.

(10) The fixed edge portion 14 comprises a fixed edge 14a having a check surface 16 for the large end face 8 of the tapered rollers 4. The check surface 16 extends at an angle, perpendicularly or approximately perpendicularly in the longitudinal section shown, to the contact surface 15. In the longitudinal section shown the inner ring 2 has the shape of a horizontal, large L, in which the horizontal arm is formed by the raceway portion 13 and the arm projecting therefrom is formed by the fixed edge portion 14. The tapered rollers 4 are arranged in a cage 17. Here the inner ring 2 at its thickest point has a wall thickness c1.

(11) The inner ring 2 and optionally also the outer ring 3 may be brought to their final shape without any cutting, by extrusion. In particular, the raceway 15 and the inner raceway 11 are cold-formed by at least one extrusion step.

(12) In the radially outer area of the fixed edge portion 14 a retaining web 30, in which the cage 17 can engage by way of retaining elements 31, is formed on the fixed edge 14a, so that the cage 17 and thereby the tapered rollers 4 are secured by positive interlock to prevent migration away from the check surface 16 and/or the fixed edge portion 14.

(13) The production of the inner ring 2 and the outer ring 3 is explained in FIG. 2:

(14) From a circular blank 18, which has been parted from a metal strip of thickness s, an annulus 19 is produced as intermediate product for the outer ring 3 by removing a center part 20. The center part 20 forms a further circular blank 21, which is a semi-finished product for the inner ring 2. A further center part 22 is removed from the further circular blank 21, so that in step I an annulus 19 is provided for the outer ring 3 and a further annulus 23 is provided as intermediate product for the inner ring 2. The procedure shown makes particularly economical use of the material of the circular blank 18. Alternatively it is also possible to use another area of the metal strip instead of the center part 20.

(15) In a preliminary forming phase in step II the annulus 19 is formed into an outer ring blank 24, the outer ring blank 24 having the shape of a sleeve. Step II in particular involves folding-over of the annulus 19. In step II the further annulus 23 is formed into an inner ring blank 25, the inner ring blank 25, however, already being formed as a contoured sleeve. Step II in particular involves folding-over and extrusion of the further annulus 23. The preliminary forming step takes the form of an extrusion process in which a temperature of the outer ring blank 24 and of the inner ring blank 25 is always less than the recrystallization temperature of the basic material.

(16) The inner ring blank 25 comprises an unfinished raceway portion 26 and an unfinished fixed edge portion 27. As is apparent from FIG. 2, the outside diameter of the unfinished fixed edge portion 27 is larger than the outside diameter of the unfinished raceway portion 26. As a whole, the inner ring blank 25 takes the form of a sleeve with an outside diameter and inside diameter constantly increasing in an axial direction. The inner ring blank 25 has a through-opening 28, which subsequently in the inner ring 2 forms the through-opening having the cylindrical inner surface 12.

(17) The unfinished raceway portion 26 is formed as a surface of a conically tapering portion both on the inner surface and on the outer surface of the inner ring blank 25.

(18) Step III is a main forming step in which the outer ring blank 24 is formed into the outer ring 3 and the inner ring blank 25 is formed into the inner ring 2 or alternatively into the inner ring 2 (possibly having a flanged edge 32, cf. FIG. 3c), in each case by means of extrusion. Here the flanged edge 32 may be formed before or after uniting the inner ring 2 with the tapered rollers 4. It must be emphasized here that the unfinished raceway portion 26 is transformed into the raceway portion 13 in such a way that the raceway 15 is already formed by the main forming step. In the same way, the inner raceway 11 of the outer ring 3 is already formed by the main forming step or step III.

(19) Although in FIG. 2 the methods for producing the inner ring 2 and the outer ring 3 are represented in parallel, these may also be performed successively, alternately or in any order relative to one another.

(20) A thickness s of the material strip 18 and hence of the annuli 19, 23 parted from this is of a dimension such that at its thickest point (cf. FIG. 1) the inner ring 2 extruded therefrom and also the outer ring 3 each have a wall thickness c1, c2 of 0.85 to 0.95.Math.s.

(21) This allows faultless forming of the inner ring 2 and the outer ring 3 by the extrusion method.

(22) FIG. 3a represents the fixed edge portion 14 in the area of the fixed edge 14a of the inner ring 2 as a detailed enlargement. It can be seen that the check surface 16 of the fixed edge 14a is of toroidal design, so that, compared to a radial plane R relative to the main axis of rotation H, a convex annular area is formed, which reaches a maximum in the center part of the annular area.

(23) In the example in FIG. 3a the retaining web 30, in which the cage 17 can engage by way of retaining elements 31 (FIG. 1), is formed on the radially outer area of the fixed edge 14a of the fixed edge portion 14, so that the cage 17 and hence the tapered rollers 4 are secured by positive interlock to prevent migration away from the check surface 16 and/or the fixed edge portion 14.

(24) FIG. 3b shows a three-dimensional view of a tapered roller 4. The large end face 8 of the tapered roller 4 is of toroidal design, so that the contact area between the large end face 8 of the tapered roller 4 and the check surface 16 is minimized, thereby reducing friction.

(25) FIG. 3c, on the other hand, shows a fixed edge portion 14 with a fixed edge 14a of a further inner ring 2, which does not comprise the retaining web 30. Instead, in the case of the further inner ring 2 a flanged edge 32 is provided, which is also produced by the main forming step and/or step III, as an axial extension of the raceway portion 13. In the subsequent production and/or assembly step the extension is bent over as a flanged edge 32.

LIST OF REFERENCE NUMERALS

(26) 1 tapered roller bearing 2,2 inner ring 3 outer ring 4 tapered rollers 5 contact angle 6 bearing surface 7 small end face 8 large end face 9 axis of rotation 10 cylindrical outer surface 11 conical inner raceway 12 cylindrical inner surface 13 raceway portion 14 fixed edge portion 14a fixed edge 15 raceway 16 check surface 17 cage 18 circular blank 19 annulus 20 center part 21 circular blank 22 center part 23 annulus 24 outer ring blank 25 inner ring blank 26 unfinished raceway portion 27 unfinished fixed edge portion 28 through-opening 30 retaining web 31 retaining elements 32 flanged edge H main axis of rotation R radial plane C1 wall thickness of the inner ring at thickest point C2 wall thickness of the outer ring at thickest point S thick annulus